Monitoring and modeling of water and related nutrient fluxes in rice-based cropping systems

为了更好地了解控制稻田系统中C和N通量的生物和水文过程，已经进行了许多研究。但很少有研究试图明确地联系水文和生态地球化学控制的养分运输在外地规模。在这个研究项目中，我们的目标是提高我们对不同水稻种植系统的水和养分储存和释放过程的理解。流域模型框架（CMF）将与土壤地球化学模型（SP 6）耦合，以模拟（1）水、C和N的垂直和横向迁移过程;（2）预测生态系统服务的反应，如水储存和净化、气体调节、养分循环和依赖于种植系统的食物供应。SP 7遵循拒绝主义框架，其中模型复杂性适应于可用数据和过程理解。最先进的分析仪器将连接到一个独特的自动采样系统，以连续测量水的同位素组成以及溶解的碳和氮溶质首次在现场。采样的沃茨包括地表水、灌溉水、地下水和水汽。腔衰荡光谱将用于测量2 H/H和18 O/16 O。同位素特征将允许估计水的平均过境时间，蒸发和蒸腾之间的分区和分离的流动路径。将安装配有流通池的高光谱紫外线光度计，用于连续测量硝酸盐和DOC。

Many studies have been conducted with the aim to better understand biologic and hydrologic processes that control C and N fluxes in rice paddy systems. But rarely have studies attempted to explicitly link the hydrological and biogeochemical controls of nutrient transport on the field scale. In this research project we aim to improve our understanding of processes that are involved in storing and releasing water and nutrients of different rice-based cropping systems. The Catchment Modeling Framework (CMF) will be coupled to the biogeochemical MOBILE-DNDC model (SP6) in to simulate (1) vertical and lateral transport processes of water, C and N and (2) to predict the reaction of ecosystem services such as water storage and purification, gas regulation, nutrient cycling and food supply in dependence of cropping systems. SP7 follows a rejectionist framework where model complexity is adapted to available data and process understanding. State-of-the-art analytical instruments will be connected to a unique automatic sampling system to continuously measure water isotopic composition as well as dissolved carbon and nitrogen solutes in situ for the first time. Waters to be sampled include surface water, irrigation water, groundwater and water vapor. Cavity Ringdown Spectroscopy will be used to measure 2H/H and 18O/16O. Isotopic signatures will allow estimating water mean transit times, partitioning between evaporation and transpiration and separating flow paths. Hyperspectral UV photometers equipped with a flow-through cell will be installed for continuous measurements of nitrate and DOC.